Method UpdateWindowManualResize

extern/imgui/imgui.cpp:6265–6413

Handle resize for: Resize Grips, Borders, Gamepad Return true when using auto-fit (double-click on resize grip)

// Handle resize for: Resize Grips, Borders, Gamepad
// Return true when using auto-fit (double-click on resize grip)
static bool ImGui::UpdateWindowManualResize(ImGuiWindow* window, const ImVec2& size_auto_fit, int* border_held, int resize_grip_count, ImU32 resize_grip_col[4], const ImRect& visibility_rect)
{
    ImGuiContext& g = *GImGui;
    ImGuiWindowFlags flags = window->Flags;

    if ((flags & ImGuiWindowFlags_NoResize) || (flags & ImGuiWindowFlags_AlwaysAutoResize) || window->AutoFitFramesX > 0 || window->AutoFitFramesY > 0)
        return false;
    if (window->WasActive == false) // Early out to avoid running this code for e.g. a hidden implicit/fallback Debug window.
        return false;

    bool ret_auto_fit = false;
    const int resize_border_count = g.IO.ConfigWindowsResizeFromEdges ? 4 : 0;
    const float grip_draw_size = IM_FLOOR(ImMax(g.FontSize * 1.35f, window->WindowRounding + 1.0f + g.FontSize * 0.2f));
    const float grip_hover_inner_size = IM_FLOOR(grip_draw_size * 0.75f);
    const float grip_hover_outer_size = g.IO.ConfigWindowsResizeFromEdges ? WINDOWS_HOVER_PADDING : 0.0f;

    ImVec2 pos_target(FLT_MAX, FLT_MAX);
    ImVec2 size_target(FLT_MAX, FLT_MAX);

    // Clip mouse interaction rectangles within the viewport rectangle (in practice the narrowing is going to happen most of the time).
    // - Not narrowing would mostly benefit the situation where OS windows _without_ decoration have a threshold for hovering when outside their limits.
    //   This is however not the case with current backends under Win32, but a custom borderless window implementation would benefit from it.
    // - When decoration are enabled we typically benefit from that distance, but then our resize elements would be conflicting with OS resize elements, so we also narrow.
    // - Note that we are unable to tell if the platform setup allows hovering with a distance threshold (on Win32, decorated window have such threshold).
    // We only clip interaction so we overwrite window->ClipRect, cannot call PushClipRect() yet as DrawList is not yet setup.
    const bool clip_with_viewport_rect = !(g.IO.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport) || (g.IO.MouseHoveredViewport != window->ViewportId) || !(window->Viewport->Flags & ImGuiViewportFlags_NoDecoration);
    if (clip_with_viewport_rect)
        window->ClipRect = window->Viewport->GetMainRect();

    // Resize grips and borders are on layer 1
    window->DC.NavLayerCurrent = ImGuiNavLayer_Menu;

    // Manual resize grips
    PushID("#RESIZE");
    for (int resize_grip_n = 0; resize_grip_n < resize_grip_count; resize_grip_n++)
    {
        const ImGuiResizeGripDef& def = resize_grip_def[resize_grip_n];
        const ImVec2 corner = ImLerp(window->Pos, window->Pos + window->Size, def.CornerPosN);

        // Using the FlattenChilds button flag we make the resize button accessible even if we are hovering over a child window
        bool hovered, held;
        ImRect resize_rect(corner - def.InnerDir * grip_hover_outer_size, corner + def.InnerDir * grip_hover_inner_size);
        if (resize_rect.Min.x > resize_rect.Max.x) ImSwap(resize_rect.Min.x, resize_rect.Max.x);
        if (resize_rect.Min.y > resize_rect.Max.y) ImSwap(resize_rect.Min.y, resize_rect.Max.y);
        ImGuiID resize_grip_id = window->GetID(resize_grip_n); // == GetWindowResizeCornerID()
        ItemAdd(resize_rect, resize_grip_id, NULL, ImGuiItemFlags_NoNav);
        ButtonBehavior(resize_rect, resize_grip_id, &hovered, &held, ImGuiButtonFlags_FlattenChildren | ImGuiButtonFlags_NoNavFocus);
        //GetForegroundDrawList(window)->AddRect(resize_rect.Min, resize_rect.Max, IM_COL32(255, 255, 0, 255));
        if (hovered || held)
            g.MouseCursor = (resize_grip_n & 1) ? ImGuiMouseCursor_ResizeNESW : ImGuiMouseCursor_ResizeNWSE;

        if (held && g.IO.MouseClickedCount[0] == 2 && resize_grip_n == 0)
        {
            // Manual auto-fit when double-clicking
            size_target = CalcWindowSizeAfterConstraint(window, size_auto_fit);
            ret_auto_fit = true;
            ClearActiveID();
        }